Security fastener



FIG. 1 is a top, rear, and right side perspective view of a security fastener showing our new design;

FIG. 2 is an enlarged top plan view thereof;

FIG. 3 is an enlarged rear elevational view thereof;

FIG. 4 is an enlarged right side elevational view thereof;

FIG. 5 is an enlarged front elevational view thereof;

FIG. 6 is an enlarged left side elevational view thereof; and,

FIG. 7 is an enlarged bottom plan view thereof. 

The ornamental design for a security fastener, as shown and described. 